The investigators propose a prospective study of 1000 low income and minority gravidas from Camden, NJ, to test the hypothesis that risk of poor pregnancy outcome is associated with an increased level of oxidative stress. They propose to measure oxidative stress, iron and iron-associated compounds, and antioxidant status at entry to care, 20 and 28 weeks gestation during pregnancy. Infant birth weight and the frequency of other poor pregnancy outcomes in the study population will serve as the outcomes. The primary objective is to determine the prognostic importance of indices for oxidative stress, specifically isoprostane 8-iso-PGF2a and 8-hydroxydeoyguanosine excretion, on low birth weight and other poor pregnancy outcomes. Secondary outcomes are: (a) to determine the prognostic importance of indices for maternal antioxidant status (total, endogenous, exogenous) on low birth weight and other poor pregnancy outcomes; (b) to determine whether indices for oxidative stress (isoprostane 8-iso-PGF2a and 8-hydroxydeoyguanosine excretion) are related to serum cotinine (a biomarker for smoking), diet (antioxidant and trace-mineral intake), ethnicity and other maternal characteristics during pregnancy; (c) to determine whether indices of oxidative stress during pregnancy are associated with biomarkers for maternal iron status and associated compounds (serum ferritin, hemoglobin, serum iron, total iron binding capacity, transferrin saturation) and 2,3 DPG.